put shell in subdir, and add nix package

shell/widgets/FontIconButton.qml

@@ -0,0 +1,48 @@
+import QtQuick
+import ".."
+
+MaterialButton {
+    id: root
+
+    property real implicitSize
+    property string iconName: ""
+    property string activeIconColor: ShellSettings.colors["inverse_primary"]
+    property string inactiveIconColor: ShellSettings.colors["inverse_surface"]
+
+    implicitWidth: this.implicitSize
+    implicitHeight: this.implicitSize
+
+    Text {
+        id: textIcon
+        text: root.iconName
+        renderType: Text.NativeRendering
+        textFormat: Text.PlainText
+        color: root.containsMouse || root.checked ? root.activeIconColor : root.inactiveIconColor 
+        horizontalAlignment: Text.AlignHCenter
+        verticalAlignment: Text.AlignVCenter
+        anchors.fill: parent
+
+        font {
+            family: "Material Symbols Outlined"
+            pointSize: Math.max(parent.height * 0.60, 11)
+
+            variableAxes: {
+                "FILL": fill
+            }
+        }
+
+        property real fill: !root.containsMouse && !root.checked ? 0 : 1
+
+        Behavior on fill {
+            NumberAnimation {
+                duration: 200
+            }
+        }
+
+        Behavior on color {
+            ColorAnimation {
+                duration: 200
+            }
+        }
+    }
+}